Life on Venus?

Many of you’ll have seen the story extensively reported within the media of the invention of the gas phosphine within the clouds of Venus – if not, yow will discover the story right here: https://www.bbc.co.uk/news/science-environment-54133538.

On Earth phosphine is produced by micro organism and it has led to the attention-grabbing hypothesis as as to whether there may very well be dwelling organisms within the clouds of Venus. I believe that it is going to be found that the phosphine is of non-biological origin however, even so, it’s attention-grabbing that the place within the Solar System with probably the most Earth-like situations (apart from the Earth itself) is at an altitude of fifty km excessive within the clouds of Venus. This was  mentioned in my submit from just a few years in the past which I’ve rewritten and re-blogged under:

Revised authentic submit below-

Until the early Nineteen Sixties the final view of Venus was that it was a planet with related situations to the Earth, however a little bit hotter as a result of it’s nearer to the Sun. Because Venus is surrounded by thick clouds, and what was beneath the clouds was an entire thriller, it allowed writers to have a free rein in imagining situations on its floor. In the years earlier than the space age Venus had been depicted in fiction as being coated by deserts, swamps, oceans, jungle and rugged mountains, and all types of unusual and unique life types have been proposed to exist there!

Image Credit Wikimedia Commons (be aware Paul French was a pseudonym utilized by Isaac Asimov)

As late as 1954, the American science fiction and fashionable science author Isaac Asimov (1920-1992) wrote the novel ‘Lucky Starr and the Oceans of Venus’. In this he assumed that Venus had a temperate local weather, a day size of 36 hours, an environment that’s 90% nitrogen and 10% carbon dioxide and a planet-wide ocean masking its floor, which was teeming with unique life types. The novel was set within the close to future when people had constructed colonies of thousands and thousands of individuals dwelling in enormous domed cities on the Venusian ocean flooring.  Only just a few years later, a really completely different image emerged, and it was clear that Asimov’s domed cities wouldn’t be taking place any time quickly.

Exploration of Venus

The exploration of Venus began for actual when Mariner 2 grew to become the primary profitable spacecraft to flee from the Earth’s gravity and cross shut to a different planet. Launched on 27 August 1962, Mariner 2 handed inside about 34,000 kilometers (21,000 miles) of Venus on 14 December 1962.

Mariner 2

Image from NASA

The devices on Mariner 2 returned a lot of information concerning the planet. Readings from them confirmed that the environment should be a lot thicker than the Earth’s and the temperature of the day and night time aspect of the planet have been each round 240 levels Celsius (ref 1).  This got here as an awesome shock and was a lot hotter than astronomers anticipated. Mariner 2 additionally made the sudden discovery that Venus, not like the Earth, has nearly no magnetic area to protect the planet from the solar wind, the stream of electrically charged particles streaming from the Sun.  In a stunning omission, Mariner 2 didn’t have a digicam, so was unable to take any photos of Venus from shut up.

During the Nineteen Sixties and Seventies  many extra spacecraft  from the Soviet Union and the US visited the planet and it progressively grew to become clear that the situations have been even harsher than Mariner 2 had urged. On 15 December 1970 the Soviet spacecraft Venera 7 landed and transmitted 23 minutes’ price of information earlier than being destroyed by the extreme warmth. On 22 October 1975 Venera 9 grew to become the primary spacecraft ever to take photos from the floor of one other planet.  In 1989 the American spacecraft Magellan orbited Venus for 4 years and, utilizing delicate radar which was capable of cross by the clouds, made a detailed map of about 98% of the Planet’s floor (ref 2).

Venus-imaged-by-Magellan

A radar view of Venus from Magellan – Image from NASA

What will we learn about Venus now?

Since the Mariner 2 mission, our information of Venus has been remodeled. We now know that the planet’s atmospheric stress is a crushing 92 instances that of the Earth and consists of 96.5% carbon dioxide (ref 3). The the rest of the environment is usually nitrogen. There is just about no oxygen and solely a small hint of water vapour.  Venus rotates so slowly {that a} night time on Venus lasts 58 Earth days.  However, the thick environment types a blanket across the planet and implies that the day and night time temperature are the identical,  round 460 levels Celsius – scorching sufficient to soften lead.

In addition, there isn’t a temperature variation with latitude: the equator and the poles of Venus are on the similar temperature. However, just like the Earth, the temperature, does fall with altitude. The highest level on Venus is named Maxwell Montes and is at an altitude of round 11km above the imply degree of the planet’s floor, about 30% increased than Mount Everest. At this altitude the temperature is a comparatively delicate 380 levels! There can be very sturdy proof that Venus is volcanically lively (ref 4).

Venus Volcanoes

Computer generated picture of lava flows on Venus – Image from Wikimedia Commons

What would it’s like to face on the floor of Venus?

Assuming we have been capable of survive the excessive temperature and crushing stress, we’d see a panorama strewn with small rocks.  The thick environment could be comparatively clear to look by, though extra distant objects would seem blurred and hazy. We would be capable to see no quite a lot of km in a horizontal route. Despite being nearer to the Sun than the Earth, the sunshine ranges are comparatively low – about the identical as in London on closely clouded day. This is as a result of the thick clouds, product of droplets of sulfuric acid, block a lot of the mild from hitting the floor. Although an observer would be capable to clearly inform the distinction between night time and day, they might by no means be capable to see the Sun.

An Earth-like setting on Venus

However, there may be an Earth-like setting on Venus. As we go increased, then, as talked about earlier than, the temperature and the atmospheric stress each lower.

Venusatmosphere

The graph above reveals how the temperature and stress  of Venus’s environment varies with altitude (from Wikimedia Commons)

Interestingly, at an altitude of about 50 km each the atmospheric temperature and stress are just like the Earth at sea degree.

In reality, at this altitude the environment of Venus is probably the most Earth-like setting, apart from Earth itself, within the Solar System. In a paper written in 2008, the NASA scientist Geoffrey Landis urged that within the far future maybe we may construct floating cities within the Venusian environment (Atkinson 2008).  The environment of Venus consists of 97% carbon dioxide, which is denser than the Earth’s environment. So, Landis identified that a big enclosed space full of a nitrogen/oxygen combine (of comparable composition to within the Earth’s environment) would float excessive above the Venusian floor in the identical way {that a} helium balloon floats within the Earth’s environment.

Floating cities on Venus

Why is Venus so scorching?

The motive why Venus is so scorching is as a result of there may be an enormous quantity of carbon dioxide within the environment. This carbon dioxide acts as a strong greenhouse gas. It lets daylight cross by however its reduces the quantity of warmth radiation which escapes again into space. It is named a greenhouse gas as a result of a greenhouse will get very popular inside on a sunny day for a similar motive. Light can cross by the glass, warming the objects inside, however the warmth rays can’t cross again out once more.

Greenhouse Gas

On Earth, carbon dioxide is simply current in small quantities and its improve from 0.029% of the environment, within the pre-industrial age, to its present worth of 0.04% is usually accepted to be accountable for an increase in world temperature of some levels. On Venus carbon dioxide makes up 96.5% of the environment and the environment is way thicker than on the Earth, which means that the greenhouse impact is totally huge. It raises the temperature by an unimaginable 500 levels above what it will be in any other case.

Some astronomers imagine that billions of years in the past, in the early days of the solar system, Venus and Earth had very related situations. Venus had loads of water and will have had a world ocean. Because Venus is nearer to the Sun it has all the time been hotter than the Earth. As readers of a previous post will know the brightness of the Sun is progressively rising at a gradual fee.

What could have occurred billions of years in the past is that at a sure cut-off date prior to now the elevated power from the Sun brought on a warming of Venus’s floor.  Because water evaporates extra quickly at increased temperatures, there was an elevated fee of evaporation from Venus’s seas and oceans. This led to an elevated focus of water vapour within the  environment.  Water vapour is a really environment friendly greenhouse gas and acted to entice warmth escaping from the floor, making it even hotter. The temperature rise led to the next floor temperature, which led to a higher fee of evaporation of water.

The course of is  known as a runaway moist greenhouse, and is illustrated within the diagram under.

Runaway Moist Greenhouse

When it reached the higher environment the water vapour was damaged down into its element parts hydrogen and oxygen.  Most of the hydrogen and oxygen produced recombined again into water vapour, however a small quantity of it was blown away by the solar wind and escaped into space.  It is the solar wind which has brought on all of the water to be progressively faraway from the Venusian environment over billions of years. The increased temperatures launched carbon dioxide, which was locked away  in rocks, into the environment thus sustaining and enhancing the greenhouse impact, even when all of the water was gone.

Recent Missions to  Venus

In the Nineteen Sixties and Seventies there was an excessive amount of curiosity in exploring Venus and a complete of 30 spacecraft have been launched to the planet. Only about half of those missions  have been profitable. However, after the Magellan mission the urge for food for exploring Venus waned considerably. It has now been almost 27 years because the launch of Magellan in 1989 and on this time solely 2 spacecraft have been despatched on missions to Venus: a probe known as Venus Express launched by the European Space Agency and a Japanese spacecraft known as Akatsuki – though three spacecraft have flown previous Venus throughout this time on missions to different planets. By comparability, in the identical time period a complete of 20 spacecraft have been launched to Mars, which most astronomers  imagine is a extra attention-grabbing object to discover, particularly because the prospect of discovering primitive types of life has not been totally dominated out. There are additionally the sensible issues that any spacecraft which lands on the floor of Venus won’t be able for final for lengthy with out being destroyed by the cruel situations, whereas  spacecraft have landed and transmitted information from the floor of Mars for a lot of years. The thick clouds over Venus additionally stop any observations of the floor by orbiting spacecraft, all that may been seen is the highest of the cloud layers.

Update 22 November 2020

There is now a video on the Explaining Science YouTube Channel which describes Venus’s orbit and phases. To view it, please click on on the hyperlink under

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Reference

Atkinson N (2008) Colonizing Venus with floating cities. Available at: http://www.universetoday.com/15570/colonizing-venus-with-floating-cities/ (Accessed: 01 February 2019)

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